| 1. |
|
|
| 2. |
|
|
| 3. |
- Rosen, S., et al.
(författare)
-
Purification and characterization of a surface lectin from the nematode-trapping fungus Arthrobotrys oligospora
- 1992
-
Ingår i: Journal of General Microbiology. - : Microbiology Society. - 0022-1287. ; 138:12, s. 2663-2672
-
Tidskriftsartikel (refereegranskat)abstract
- Several studies have indicated that the capture of nematodes by the nematophagous fungus Arthrobotrys oligospora is mediated by a lectin on the fungal surface. One of the major surface proteins of this fungus showed haemagglutinating activity and was isolated by affinity chromatography using a mucin Sepharose column. Biochemical analysis showed that the protein was a dimeric glycoprotein with a molecular mass of 36 kDa and an isoelectric point of pH 6.5, and contained no sulphur amino acids. The protein was N-terminally blocked; four internal peptides were sequenced, and showed no significant similarity to sequences in the Swiss-Prot or PIR databases. The haemagglutinating activity of the isolated protein was not inhibited by any of the mono- or disaccharides tested, but it was inhibited by the glycoproteins fetuin and mucin. The haemagglutinating activity changed after incubating the protein in buffers of different pH, with maximal activity at pH 11.0 and no activity at pH 2.8. The lectin was tested for different enzymic activities but none were detected. Analysis of the haemagglutinating activity in various cell fractions indicated that the protein was associated with extracellular polymer layers and with the cell wall of the fungus. About the same amount of the haemagglutinating protein was recovered from samples of vegetative mycelium and of mycelium containing nematode-trapping cells.
|
|
| 4. |
|
|
| 5. |
- Tunlid, A., et al.
(författare)
-
Purification and characterization of an extracellular serine protease from the nematode-trapping fungus Arthrobotrys oligospora
- 1994
-
Ingår i: Microbiology. - : Microbiology Society. - 1350-0872 .- 1465-2080. ; 140:7, s. 1687-1695
-
Tidskriftsartikel (refereegranskat)abstract
- When grown in liquid cultures allowing the formation of nematode traps, the fungus Arthrobotrys oligospora produced two extracellular proteases hydrolysing the chromogenic substrate Azocoll. The protease activity was separated into two fractions (FI and FII) using anion-exchange chromatography. In bioassays, protease(s) present in FII immobilized the free-living nematode Panagrellus redivivus indicating that the enzyme(s) might be involved in the infection of nematodes. A protease designated PII was purified from FII to apparent homogeneity by hydrophobic interaction and size-exclusion chromatography, resulting in an approximately 15-fold increase in specific activity. The purified enzyme was glycosylated, had a molecular mass of approximately 35 kDa (gel filtration) and an isoelectric point of pH 4.6. PII immobilized P. redivivus in bioassays and hydrolysed proteins of the purified cuticle. The enzyme hydrolysed several protein substrates including casein, bovine serum albumin and gelatin, but not native collagen. Examination of substrate specificity with synthetic peptides showed that PII readily hydrolysed tripeptides with aromatic or basic amino acids including N-benzoyl-L-phenylalanyl-L-valyl-L-arginine-4-nitroanilide (Bz-Phe-Val-Arg-NA) and succinyl-glycyl-glycyl-L-phenylalanine-4-nitroanilide (Suc-Gly-Gly-Phe-NA). Mono-peptides were hydrolysed at considerably slower rates. PII had an optimum activity between pH 7 and 9 and was susceptible to autodegradation. PII was inhibited by several serine protease inhibitors including phenylmethylsulfonyl fluoride (PMSF), chymostatin and antipain. The protease was N-terminally blocked, but the sequence of one internal peptide showed a high homology with a region containing the active site histidine residue of the subtilisin family of serine proteases.
|
|
| 6. |
- Wirsen, A., et al.
(författare)
-
Quantified EEG and cortical evoked responses in patients with chronic traumatic frontal lesions
- 1992
-
Ingår i: Electroencephalography and Clinical Neurophysiology / Evoked Potentials Section. - : Elsevier BV. - 0168-5597. ; 84:2, s. 127-138
-
Tidskriftsartikel (refereegranskat)abstract
- Eighteen frontal trauma patients and 17 age-matched control subjects had quantified EEGs and measurements of sensory (SEP) and auditory evoked potentials (P300) using a Biologic Brain Atlas III system. The findings were compared to the conventional paper EEG, and to the frontal lesion volumes, severity of head injury, and outcome variables. The quantified EEG confirmed the pathological findings detected by visual inspection, but some regional abnormalities were more easily detected by topographic mapping. The regional distribution of pathological slowing corresponded well with the morphological lesions in most patients. The modal frequency of EEG correlated both with lesion volume and injury severity and with the outcome variables. There were no pathological findings in the SEPs, and all but one patient had clearly distinguishable P300 responses. There was a significant reduction in P300 amplitude in the frontal patients at the anterior, but not at the posterior electrodes. The topographical distribution of the P300 changes corresponded well with the morphological lesions. Our findings indicate that the P300 potential is, in part, dependent upon the prefrontal cortical areas. The present study thus supports P300 investigations which have shown amplitude reduction in other disorders (e.g., schizophrenia) with a presumed prefrontal dysfunction.
|
|
